Effect of Wall, Roof, and Window-to-Wall Ratio on the Cooling and Heating Load of a Building in India

This study examines the impact of various combinations of walls, roofs, and window-to-wall ratios (WWRs) on the cooling and heating loads of residential buildings in India's composite climatic zone. Utilizing EnergyPlus and eQuest simulations, the thermal performance of three building types is analyzed across 32 cases involving two types of walls (W1, W2), roofs (R1, R2), and WWRs of 10%, 20%, 30%, and 40%. The results indicate that Case 29 (W2 R2 N2 WWR1), characterized by a north-facing orientation, square-shaped design, and a 10% WWR, achieves the lowest cooling and heating loads among all configurations. Specifically, in Building 1, this configuration reduces cooling loads by 26.0% (from 204 to 151 kBTU/h) and heating loads by 28.6% (from 224 to 160 kBTU/h) compared to the highest load scenario, Case 4 (W1 R1 N1 WWR4, west-facing orientation, square-shaped design, and 40% WWR). Similar trends are observed for Buildings 2 and 3. These findings underscore the critical role of optimizing building envelope parameters, particularly orientation, shape, and WWR, in achieving significant energy savings. The insights provided by this study can aid architects, engineers, and policymakers in designing energy-efficient residential buildings.